This invention relates to a disposable diaper and more particularly to such a diaper improved so that occurrence of urination can be visually recognized as soon as possible from the outside of the diaper.
Japanese Patent Application Disclosure No. 1993-200063 describes a breathable liquid-impervious sheet used as a backsheet in a disposable diaper. This sheet comprises an polyolefine plastic sheet containing grains of inorganic filler. The sheet presenting surfaces made rough by the presence of the grains is heat-embossed so that the heat-embossed regions may be smoothed. The smoothed regions of the sheet exhibit a sufficiently high light transmissivity to facilitate an absorbent pad wetted with urine to be visually recognized from the outside of the backsheet. Regions remaining rough, on the other hand, exhibit a poor light transmissivity and does not contribute to visual recognition of urination. These rough regions rather contribute to concealment of the stained absorbent pad.
The sheet of prior art having both the high light transmissivity and the concealing property must be subjected to a step of heat-embossing in addition to a step of sheet extrusion. With a consequence, a manufacturing cost may correspondingly increase.
It is an object of this invention to improve the backsheet used in the disposable diaper having both the high light transmissivity and the concealing property so as to be supplied at a low cost.
According to this invention, there is provided a disposable diaper comprising a liquid-pervious topsheet, a breathable liquid-impervious backsheet and a liquid-absorbent core disposed between these two sheets, wherein: the backsheet is made of a stretched plastic film containing grains of inorganic filler, the backsheet presents surfaces roughed by the presence of the grains and has a moisture permeability of 800-3000 g/m2xc2x724 hr and a total light transmissivity of 60-85%.
This invention includes preferred embodiments as will be described:
The backsheet is bonded to the core by means of hot melt adhesive agent to ensure that a situation in which the core has been wetted with urine can be visually recognized from the outside of the backsheet more easily in regions of the hot melt adhesive agent than in the remaining regions.
Regions of the backsheet having been applied with the hot melt adhesive agent are substantially smoother than the remaining regions.